Method of manufacturing glass plates

Abstract

Increase the taper angle of the through-hole formed in the glass plate. [Solution] A method for manufacturing a glass plate, comprising a modification step S1 in which the area to be formed of through holes is modified by irradiation with laser light, and an etching step S2 after the modification step in which the glass plate is immersed in an etching solution containing HF to form through holes in the area to be formed. In the etching step S2, when the temperature of the etching solution is x [°C] and the concentration of HF in the etching solution 6 is y [mol / L], the relationship -0.040x + 2.4 ≤ y ≤ -0.040x + 3.2 holds.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a glass plate having through holes.

Background Art

[0002] For example, as a substrate such as a tiling display (micro LED, etc.), a borderless display, a glass interposer, etc., a glass plate having fine through holes for wiring (through electrodes, etc.) is used.

[0003] As a method for manufacturing this type of glass plate having through holes, for example, a modification step of modifying a portion where a through hole is to be formed in the glass plate by irradiating laser light, and after the modification step, an etching step of forming a through hole in the portion where the through hole is to be formed by etching (for example, refer to Patent Document 1).

[0004] The modified portion modified in the modification step has a higher etching rate than the non-modified portion that was not modified in the modification step. Therefore, in the etching step, the modified portion is preferentially removed. Therefore, if a modified portion is formed in the portion where the through hole is to be formed, a through hole can be formed in the portion where the through hole is to be formed by etching.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When forming through holes as described above, the portion of the glass plate closer to the main surface is more easily etched due to prolonged contact with the etching solution. As a result, the diameter of the through hole becomes larger in the portion closer to the main surface than in the center in the thickness direction, and the inner wall surface of the through hole becomes tapered. If the taper angle of the through hole becomes too small, the diameter of the hole in the main surface of the glass plate becomes too large, making it impossible to form high-density through holes, which can lead to problems such as the inability to form a high-resolution pattern on the main surface of the glass plate. Here, the taper angle of the through hole is the angle between the direction perpendicular to the thickness direction and the inner wall surface of the through hole (see θ2 in Figure 6, described later).

[0007] The present invention aims to increase the taper angle of through holes formed in glass plates. [Means for solving the problem]

[0008] The inventors have diligently researched and obtained the following findings: In the etching process, by reducing the etching rate, the selectivity ratio (etching rate of the modified portion / etching rate of the unmodified portion) between the etching rate of the unmodified portion (which is in a reaction-limiting state) and the etching rate of the modified portion (which is in a diffusion-limiting state) can be increased. A larger selectivity ratio promotes the preferential removal of the modified portion, allowing for a larger taper angle of the through-hole. However, the selectivity ratio does not always increase monotonically with decreasing etching reaction rate. In other words, if the etching reaction rate is reduced too much, at some point the modified portion also becomes the etching reaction limiting portion, and the selectivity ratio shifts from an increasing trend to a decreasing trend. Furthermore, since the diffusion rate and reaction rate have different temperature dependencies, the concentration of the etching solution at which diffusion-limiting rate control transitions to reaction-limiting rate control also differs depending on the temperature of the etching solution. Therefore, it is necessary to select the optimal etching solution concentration according to the temperature of the etching solution.

[0009] (1) The present invention, devised to solve the above problems, is a method for manufacturing a glass plate having a first main surface, a second main surface, and a through hole penetrating between the first main surface and the second main surface, and is characterized in that it comprises a modification step of modifying the area where the through hole is to be formed by irradiation with laser light, and an etching step after the modification step of immersing the glass plate in an etching solution containing HF to form a through hole in the area where the through hole is to be formed, wherein in the etching step, when the temperature of the etching solution is x [°C] and the concentration of HF in the etching solution is y [mol / L], the relationship -0.04x + 2.4 ≤ y ≤ -0.04x + 3.2 holds.

[0010] In this way, by performing etching in such a manner that the above relationship holds true during the etching process, the optimal HF concentration of the etching solution can be selected according to the temperature of the etching solution. As a result, through holes with a large taper angle can be formed.

[0011] (2) In the configuration of (1) above, the temperature of the etching solution is preferably 5°C or higher and 30°C or lower.

[0012] If the etching solution temperature is too low, it may freeze, making the etching process impossible. On the other hand, if the etching solution temperature is too high, vaporization will occur, making it difficult to maintain a constant concentration. By keeping the etching solution temperature within the above numerical range, these problems can be suppressed. In other words, it is possible to prevent the etching solution from freezing while stabilizing its concentration.

[0013] (3) In the configuration of (1) or (2) above, the etching solution preferably further contains HCl.

[0014] Etching using an etching solution containing HF generates fluorides containing glass components as poorly soluble byproducts. These fluorides can reduce productivity by causing a decrease in etching rate and the generation of defects. However, by using a mixed acid of HF and HCl as the etching solution, as described above, the fluorides can be efficiently removed by replacing them with soluble chlorides, thereby suppressing the decrease in productivity.

[0015] (4) In any of the configurations (1) to (3) above, in the etching process, when the etching rate in the thickness direction of the modified portion modified in the modification process is V1 [μm / min] and the etching rate in the thickness direction of the unmodified portion not modified in the modification process is V2 [μm / min], it is preferable that the selectivity ratio (V1 / V2) between V1 and V2 is 3.0 or more.

[0016] This method promotes the preferential removal of the modified material and allows for the formation of through-holes with a favorable taper angle.

[0017] (5) In any of the configurations described in (1) to (4) above, the glass plate is preferably alkali-free glass.

[0018] In this way, it is possible to manufacture glass plates with through-holes that are ideal for display applications. [Effects of the Invention]

[0019] According to the present invention, the taper angle of the through hole formed in the glass plate can be increased. [Brief explanation of the drawing]

[0020] [Figure 1] This is a flowchart showing a method for manufacturing a glass plate according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view showing the modification process. [Figure 3] This is a cross-sectional view showing the etching process. [Figure 4]A cross-sectional view of a glass plate in an etching process, showing a state before a planned formation part of the glass plate penetrates. [Figure 5] A cross-sectional view of a glass plate in an etching process, showing a state when a planned formation part of the glass plate has penetrated. [Figure 6] A cross-sectional view of a glass plate having through-holes. [Figure 7] A graph showing the relationship between the HF concentration of an etching solution and the selectivity ratio. [Figure 8] A graph showing the relationship between the HF concentration of an etching solution and the taper angle of a through-hole. [Figure 9] A graph showing the relationship between the temperature of an etching solution and the optimum HF concentration of the etching solution.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

[0022] As shown in FIG. 1, the method for manufacturing a glass plate according to the present embodiment includes a reforming step S1 and an etching step S2.

[0023] (Reforming Step) As shown in FIG. 2, the reforming step S1 is a step of reforming a planned formation part 3 of a through-hole in the glass plate 2 by laser light L irradiated from a laser device 1. By the reforming step S1, the planned formation part 3 includes a reformed part 4 that has been reformed. The reformed part 4 extends along the plate thickness direction and has a property of being more easily etched than an un-reformed part 5 that has not been reformed. The reformed part 4 is preferably formed continuously along the plate thickness direction, but may be formed intermittently along the plate thickness direction. When a plurality of through-holes 10 (see FIG. 6 described later) are formed in the glass plate 2, a plurality of planned formation parts 3 including the reformed part 4 are also formed.

[0024] The type and irradiation conditions of the laser beam L are not particularly limited, as long as it can form a modified portion 4 in the area to be formed 3. In this embodiment, the laser beam L is a short-pulse laser beam (picosecond laser beam, nanosecond laser beam, femtosecond laser beam). The diameter W of the modified portion 4 can be adjusted by the spot diameter of the laser beam L, etc.

[0025] The glass plate 2 can be, for example, a glass plate made of alkali-free glass, and preferably contains, in mass%, SiO2 58-68%, Al2O3 15-23% (particularly 17-21%), B2O3 3-9% (particularly 5-7%), Li2O+Na2O+K2O 0-1% (particularly 0-0.5%), MgO 1-6% (particularly 1-4%), CaO 3-13% (particularly 5-10%), SrO 0-10% (particularly 0.1-3%), and BaO 0-10% (particularly 2-7%). In this way, it can be suitably used as a glass substrate for displays.

[0026] (Etching process) Etching step S2 is a step in which through holes 10 penetrate in the thickness direction between the first main surface 2a and the second main surface 2b of the glass plate 2 in the part to be formed 3, which includes the modified part 4.

[0027] As shown in Figure 3, in etching step S2, the glass plate 2 is immersed in etching solution 6 containing HF. The etching solution 6 is stored in the etching tank 7. In this embodiment, etching proceeds simultaneously from both sides of the first main surface 2a and the second main surface 2b of the glass plate 2.

[0028] As the etching solution 6 containing HF, for example, an aqueous solution containing only HF as the acid, or an aqueous solution containing HF and at least one acid selected from HCl, HNO3, and H2SO4 can be used. By using a mixed acid of HCl and HF as the etching solution 6, as in the latter case, sparingly soluble fluoride produced as a byproduct during etching can be efficiently removed by replacing it with soluble chloride, thereby suppressing a decrease in productivity. In particular, it is preferable to use a mixed acid of HCl and HF as the etching solution 6.

[0029] When etching step S2 is performed after modification step S1, the modified portion 4 has a higher etching rate than the unmodified portion 5, so the modified portion 4 is preferentially removed. As a result, as shown in Figures 4 to 6, the portion 3 to be formed, including the modified portion 4, is gradually removed by etching. In Figures 4 to 6, reference numerals 2aо and 2bо indicate the positions of the main surfaces 2a and 2b before etching.

[0030] More specifically, as shown in Figure 4, in the initial stages of the etching process S2, the planned formation portion 3 does not penetrate in the thickness direction of the plate, and a bottomed recess 8 is formed in the planned formation portion 3 on both the first main surface 2a side and the second main surface 2b side, having a tapered inner wall surface 8a whose opening area decreases toward the center in the thickness direction.

[0031] As shown in Figure 5, in the middle of the etching process S2, the planned formation portion 3 penetrates in the thickness direction, and an initial through-hole 9 is formed. The initial through-hole 9 has a tapered first inner wall surface 9a from the first main surface 2a side toward the center in the thickness direction, and a tapered second inner wall surface 9b from the second main surface 2b side toward the center in the thickness direction, with both inner wall surfaces 9a and 9b connected to each other in the center in the thickness direction.

[0032] Towards the end of the etching process S2, the diameter of the initial through-hole 9 expands, and ultimately a through-hole 10 is formed having a tapered first inner wall surface 10a and a second inner wall surface 10b as shown in Figure 6.

[0033] In etching step S2, when the temperature of the etching solution 6 is x [°C] and the HF concentration of the etching solution 6 is y [mol / L], the relationship -0.04x + 2.4 ≤ y ≤ -0.04x + 3.2 holds true. In this way, the optimal HF concentration of the etching solution 6 can be selected to match the temperature of the etching solution 6. Therefore, the selectivity ratio (V1 / V2) between the etching rate V1 [μm / min] in the thickness direction of the modified section 4 and the etching rate V2 [μm / min] in the thickness direction of the unmodified section 5 can be increased. As a result, the taper angle θ1 of the initial through-hole 9 when the planned section 3 penetrates becomes larger. The taper angle θ2 of the final through-hole 10 largely depends on the taper angle θ1 of the initial through-hole 9, so if the taper angle θ1 of the initial through-hole 9 becomes larger, the taper angle θ2 of the through-hole 10 will inevitably become larger as well.

[0034] The taper angle θ1 of the initial through hole 9 is preferably 75° or more, more preferably 80° or more, and even more preferably 84° or more. Ideally, the taper angle θ1 of the initial through hole 9 is 90°, but considering the productivity of the glass plate 2, it can be, for example, 85° or less.

[0035] The temperature of the etching solution 6 is preferably 5°C or higher. Preferably, the temperature of the etching solution 6 is 30°C or lower, more preferably 20°C or lower, and even more preferably 15°C or lower. This prevents problems such as the etching solution 6 becoming too cold and freezing, or the etching solution 6 becoming too hot and causing a large change in HF concentration. Note that changes in HF concentration can occur due to the vaporization of HF and water contained in the etching solution 6.

[0036] In etching step S2, the selectivity ratio (V1 / V2) is preferably 3.0 or higher, more preferably 6.0 or higher, and even more preferably 10.0 or higher. This promotes preferential removal of the modified portion 4, enabling the formation of an initial through-hole 9 with a good taper angle θ1. As a result, it becomes easier to form a through-hole 10 with a large taper angle θ2. On the other hand, the upper limit of the selectivity ratio can be, for example, 12 or less. Here, the selectivity ratio (V1 / V2) can be determined, for example, as shown in Figure 5, by the ratio (E1 / E2) of the etching amount E2 of the unmodified portion 5 in the thickness direction when the initial through-hole 9 is formed and the planned portion 3 is penetrated, to the etching amount E1 of the modified portion 4 in the thickness direction when the initial through-hole 9 is formed and the planned portion 3 is penetrated. The etching amounts E1 and E2 are determined based on the positions 2aо and / or 2bо of the main surface 2a and / or main surface 2b of the glass plate 2 before etching. Specifically, for example, the etching amount E1 of the modified portion 4 can be determined by (thickness of glass plate 2 before etching) / 2, and the etching amount E2 of the unmodified portion 5 can be determined by [(thickness of glass plate 2 before etching) - (thickness of glass plate 2 when the planned portion 3 is penetrated)] / 2. When determining the selectivity ratio (V1 / V2), the etching amounts E1 and E2 may be determined from one glass plate 2, or, if the processing conditions are the same, the etching amounts E1 and E2 may be determined from two glass plates 2 respectively.

[0037] Furthermore, the present invention is not limited to the configuration of the above embodiments, nor is it limited to the effects described above. The present invention can be modified in various ways without departing from the spirit of the invention.

[0038] In the above embodiment, the etching step S2 may include a measurement step for measuring the temperature of the etching solution 6 and the HF concentration of the etching solution 6, and an adjustment step for adjusting at least one of the temperature of the etching solution 6 and the HF concentration of the etching solution 6 based on the results of the measurement step. In this way, the optimal HF concentration of the etching solution 6 that matches the temperature of the etching solution 6 can be reliably maintained.

[0039] In the above embodiment, the etching step S2 may include a cleaning step in which the glass plate 2 is removed from the etching solution 6 and washed. This allows for efficient removal of impurities such as fluoride formed in the etching step S2.

[0040] In the above embodiment, if multiple through holes 10 are formed, the multiple through holes 10 may be formed at a high density and in a regular manner.

[0041] In the above embodiment, the etching solution 6 may be stirred while the etching process S2 is being executed. Methods for stirring the etching solution 6 include vibrating the etching solution 6 with ultrasonic waves, or rotating or vibrating a stirring member to stir the etching solution 6. [Examples]

[0042] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

[0043] A glass plate made of alkali-free glass (OA-11 manufactured by Nippon Electric Glass Co., Ltd.) with a thickness of 500 μm before etching was prepared. Next, a modified area was formed in the area of ​​the prepared glass plate to be modified using short-pulse laser light. Subsequently, the glass plate with the modified area was etched by immersion in an etching solution containing HF, thereby forming through holes in the area to be modified.

[0044] As the first evaluation test, when forming through holes as described above, we evaluated how the selectivity ratio (etching rate V1 in the thickness direction of the modified section / etching rate V2 in the thickness direction of the unmodified section) changed when the HF concentration of the etching solution was varied for each of the etching solution temperatures of 5°C, 10°C, 20°C, and 30°C. The results of the first evaluation test are shown in Figure 7.

[0045] Furthermore, as a second evaluation test, when forming through holes as described above, we evaluated how the taper angle of the initial through holes changed when the HF concentration of the etching solution was varied for each of the etching solution temperatures: 5°C, 10°C, 20°C, and 30°C. The results of the second evaluation test are shown in Figure 8.

[0046] As can be seen from the results in Figure 7, in all cases where the etching solution temperature is 5°C, 10°C, 20°C, or 30°C, there is a peak where the selectivity ratio is maximum as the HF concentration of the etching solution decreases. This is because, as the HF concentration of the etching solution decreases, the etching reaction in the modification section shifts from diffusion-controlled to reaction-controlled. In other words, the peak where the selectivity ratio is maximum is shown at the HF concentration at which the etching reaction in the modification section shifts from diffusion-controlled to reaction-controlled.

[0047] Furthermore, the results in Figure 8 confirm that, regardless of whether the etching solution temperature is 5°C, 10°C, 20°C, or 30°C, there is a peak where the taper angle is maximum during the process of decreasing HF concentration in the etching solution. It should be noted that the pattern of change in the taper angle in Figure 8 corresponds to the pattern of change in the selectivity ratio in Figure 7. In other words, regardless of whether the etching solution temperature is 5°C, 10°C, 20°C, or 30°C, it can be confirmed that the taper angle increases with increasing selectivity.

[0048] Then, in the results shown in Figure 8, the data for etching solution temperatures of 5°C, 10°C, 20°C, and 30°C were fitted using a quadratic function, and the HF concentration of the etching solution when the taper angle was maximized (optimal HF concentration) was determined for each temperature. Figure 9 shows the relationship between the etching solution temperature and the optimal HF concentration of the etching solution.

[0049] If the etching solution temperature is x [°C] and the optimal HF concentration of the etching solution is y [mol / L], the relationship between the optimal HF concentration of the etching solution and the etching solution temperature shown in Figure 9 can be approximated by the following equation (1). y = -0.04x + 2.8 (1)

[0050] Furthermore, as shown in the results in Figure 8, the decrease in the taper angle of the initial through-hole was 0.1° or less when the HF concentration of the etching solution was within the range of ±0.4 [mol / L] of the optimal HF concentration of the etching solution. Therefore, it can be seen that if the relationship between the optimal HF concentration of the etching solution and the temperature of the etching solution satisfies equation (2) below, the taper angle of the initial through-hole can be maintained at a large level. -0.04x+2.4≦y≦-0.04x+3.2 (2)

[0051] In Figure 8, when the etching solution temperature is 5°C, the four data points from the left represent a comparative example that does not satisfy equation (2), while the two data points from the right represent an embodiment that satisfies equation (2). When the etching solution temperature is 10°C, the three data points from the left and the one data point from the right represent a comparative example that does not satisfy equation (2), while the two data points in between represent an embodiment that satisfies equation (2). When the etching solution temperature is 20°C, the three data points from the left and the two data points from the right represent a comparative example that does not satisfy equation (2), while the one data point in between represents an embodiment that satisfies equation (2). When the etching solution temperature is 30°C, the two data points from the left and the two data points from the right represent a comparative example that does not satisfy equation (2), while the two data points in between represent an embodiment that satisfies equation (2). [Explanation of symbols]

[0052] 1. Laser device 2 glass plates 3. Planned Formation 4. Modification section 5. Unmodified parts 6 Etching solution 7 Etching tank 8 recesses 9 Initial through hole 10 Through holes L Laser light S1 Modification Process S2 Etching process θ1 Taper angle of the initial through hole θ2 Taper angle of through hole

Claims

1. A method for manufacturing a glass plate having a first main surface, a second main surface, and a through hole penetrating between the first main surface and the second main surface, The process includes a modification step of modifying the area where the through-hole is to be formed by irradiating it with laser light, and an etching step after the modification step of immersing the glass plate in an etching solution containing HF to form the through-hole in the area where the through-hole is to be formed. A method for manufacturing a glass plate, characterized in that, in the etching step, when the temperature of the etching solution is x [°C] and the HF concentration of the etching solution is y [mol / L], the relationship -0.04x + 2.4 ≤ y ≤ -0.04x + 3.2 holds true.

2. The method for manufacturing a glass plate according to claim 1, wherein the temperature of the etching solution is 5°C or more and 30°C or less.

3. The method for manufacturing a glass plate according to claim 1 or 2, wherein the etching solution further comprises HCl.

4. The method for manufacturing a glass plate according to claim 1 or 2, wherein in the etching step, when the etching rate in the thickness direction of the modified portion modified in the modification step is V1 [μm / min] and the etching rate in the thickness direction of the unmodified portion not modified in the modification step is V2 [μm / min], the selectivity ratio (V1 / V2) between V1 and V2 is 3.0 or more.

5. The method for manufacturing a glass plate according to claim 1 or 2, wherein the glass plate is alkali-free glass.

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